In 3GPP release-11 (3GPP Rel-11) and previous versions, some subject researches for interference elimination have been performed for Picocells and Femtocells. The Picocell provides a solution for distributing hotspot services. According to study, it can be determined that comparing to a Macrocell, emission power of the Picocell is smaller, and the Picocell cannot effectively distribute services, and load of the Picocell is only 60%. Therefore, 3GPP provides a cell range expansion (CRE) technology. By setting an access bias, terminals have priority access to a cell having the Picocell. However, in CRE regions, the terminals which have access to the Picocell service may receive a great interference power from the macrocell. For this, 3GPP has developed Eicic and Feicic subjects. By way of almost bland subframe (ABS) technology, control signals of the macrocell and the Picocell are time multiplexed, which can ensure reliability of control signal channels.
The Femtocell is a family base station established by users, and connected to core network via ADSL or other. The Femtocells are established randomly in doors. Without network planning of an operator, a number of Femtocells may be arranged closely. The Femtocell always employs close subscribe group (CSG) configurations, that is, only provides services for authorized users. The Femtocell can bring great interference for nearby unauthorized users. For this problem, 3GPP develops interference management manners, e.g., power control of the Femtocell, frequency multiplexing of control signal channels, to solve interference problems. However, these interference management manners cannot work well in the region where the Femtocells are distributed densely.
To provide better coverage and service distribution, a number of micro cells may be established densely, and mutual interference is very great. Some companies provide a cell on and off manner to close the cells where data transmission is temporarily not needed to eliminate interference.
However, when the cells where data transmission is not needed are directly closed, terminals cannot search the cells in the dormant state, and cannot awaken the cells when data transmission is needed.